Assessing working memory capacity through picture span and feature binding with visual-graphic symbols during a visual search task with typical children and adults.

This study investigated developmental memory capacity through picture span and feature binding. Participants included third grade students and college age adults with typical development. Picture span was used to assess working memory capacity when participants were asked to identify, locate, and sequence common visual-graphic symbols from experimental grid displays. Feature binding was assessed to evaluate how symbols, locations and sequences are bound together in working memory. The features assessed included symbol recall, location recall, symbol location binding, symbol sequence binding, and location sequence binding. All participants were shown a sequence of visual-graphic symbols on 4 by 4 stimulus grid displays. Participants were then asked to remember symbols amidst distractor symbols and place them in the correct location on a response grid, using the correct sequence. Results revealed expected developmental differences between third graders and adults on picture span. Significant differences between third graders and adults were also obtained for symbol sequence and location sequence binding. Performance for both groups on the sequence binding features were marginal (i.e., 30% of third graders and 60% of adults binding symbol sequence; 27% of third graders and 52% of adults binding location sequence). These results convey the influence of picture span and feature binding on working memory capacity. Implications are discussed in relation to theoretical models on working memory and compensatory strategies to increase feature binding with target and contextual memory.

Developmental memory capacity resources of typical children retrieving picture communication symbols using direct selection and visual linear scanning with fixed communication displays.

PURPOSE: This study examined the cognitive demands of 2 selection techniques in augmentative and alternative communication (AAC), direct selection, and visual linear scanning, by determining the memory retrieval abilities of typically developing children when presented with fixed communication displays. METHOD: One hundred twenty typical children from kindergarten, 1st, and 3rd grades were randomly assigned to either a direct selection or visual linear scanning group. Memory retrieval was assessed through word span using Picture Communication Symbols (PCSs). Participants were presented various numbers and arrays of PCSs and asked to retrieve them by placing identical graphic symbols on fixed communication displays with grid layouts. RESULTS: The results revealed that participants were able to retrieve more PCSs during direct selection than scanning. Additionally, 3rd-grade children retrieved more PCSs than kindergarten and 1st-grade children. An analysis on the type of errors during retrieval indicated that children were more successful at retrieving the correct PCSs than the designated location of those symbols on fixed communication displays. CONCLUSIONS: AAC practitioners should consider using direct selection over scanning whenever possible and account for anticipatory monitoring and pulses when scanning is used in the service delivery of children with little or no functional speech. Also, researchers should continue to investigate AAC selection techniques in relationship to working memory resources.